signal: Add unsafe_get_compat_sigset()

In the same way as commit 14026b94ccfe ("signal: Add
unsafe_put_compat_sigset()"), this time add
unsafe_get_compat_sigset() macro which is the 'unsafe'
version of get_compat_sigset()

For the bigendian, use unsafe_get_user() directly
to avoid intermediate copy through the stack.

For the littleendian, use a straight unsafe_copy_from_user().

This commit adds the generic fallback for unsafe_copy_from_user().
Architectures wanting to use unsafe_get_compat_sigset() have to
make sure they have their own unsafe_copy_from_user().

Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/b05bf434ee13c76bc9df5f02653a10db5e7b54e5.1616151715.git.christophe.leroy@csgroup.eu

diff --git a/include/linux/compat.h b/include/linux/compat.h
index 6e65be75360321444993b4f58df13d4d9fb04562..5112c3e35782faa50fa2b30cbbe14bb3b2f35f94 100644 (file)
--- a/include/linux/compat.h
+++ b/include/linux/compat.h
@@ -465,6 +465,34 @@ put_compat_sigset(compat_sigset_t __user *compat, const sigset_t *set,
                unsafe_put_user(__s->sig[0], &__c->sig[0], label);      \
        }                                                               \
 } while (0)
+
+#define unsafe_get_compat_sigset(set, compat, label) do {              \
+       const compat_sigset_t __user *__c = compat;                     \
+       compat_sigset_word hi, lo;                                      \
+       sigset_t *__s = set;                                            \
+                                                                       \
+       switch (_NSIG_WORDS) {                                          \
+       case 4:                                                         \
+               unsafe_get_user(lo, &__c->sig[7], label);               \
+               unsafe_get_user(hi, &__c->sig[6], label);               \
+               __s->sig[3] = hi | (((long)lo) << 32);                  \
+               fallthrough;                                            \
+       case 3:                                                         \
+               unsafe_get_user(lo, &__c->sig[5], label);               \
+               unsafe_get_user(hi, &__c->sig[4], label);               \
+               __s->sig[2] = hi | (((long)lo) << 32);                  \
+               fallthrough;                                            \
+       case 2:                                                         \
+               unsafe_get_user(lo, &__c->sig[3], label);               \
+               unsafe_get_user(hi, &__c->sig[2], label);               \
+               __s->sig[1] = hi | (((long)lo) << 32);                  \
+               fallthrough;                                            \
+       case 1:                                                         \
+               unsafe_get_user(lo, &__c->sig[1], label);               \
+               unsafe_get_user(hi, &__c->sig[0], label);               \
+               __s->sig[0] = hi | (((long)lo) << 32);                  \
+       }                                                               \
+} while (0)
 #else
 #define unsafe_put_compat_sigset(compat, set, label) do {              \
        compat_sigset_t __user *__c = compat;                           \
@@ -472,6 +500,13 @@ put_compat_sigset(compat_sigset_t __user *compat, const sigset_t *set,
                                                                        \
        unsafe_copy_to_user(__c, __s, sizeof(*__c), label);             \
 } while (0)
+
+#define unsafe_get_compat_sigset(set, compat, label) do {              \
+       const compat_sigset_t __user *__c = compat;                     \
+       sigset_t *__s = set;                                            \
+                                                                       \
+       unsafe_copy_from_user(__s, __c, sizeof(*__c), label);           \
+} while (0)
 #endif
 
 extern int compat_ptrace_request(struct task_struct *child,

diff --git a/include/linux/uaccess.h b/include/linux/uaccess.h
index c7c6e8b8344d49871fd65524a30b5e1e1d02cbf6..c05e903cef02a3daa471c83a3593c34a168cd02e 100644 (file)
--- a/include/linux/uaccess.h
+++ b/include/linux/uaccess.h
@@ -397,6 +397,7 @@ long strnlen_user_nofault(const void __user *unsafe_addr, long count);
 #define unsafe_get_user(x,p,e) unsafe_op_wrap(__get_user(x,p),e)
 #define unsafe_put_user(x,p,e) unsafe_op_wrap(__put_user(x,p),e)
 #define unsafe_copy_to_user(d,s,l,e) unsafe_op_wrap(__copy_to_user(d,s,l),e)
+#define unsafe_copy_from_user(d,s,l,e) unsafe_op_wrap(__copy_from_user(d,s,l),e)
 static inline unsigned long user_access_save(void) { return 0UL; }
 static inline void user_access_restore(unsigned long flags) { }
 #endif